(1) Field of the Invention
The present invention relates to a sound wave control device, and can be used for reducing noise and improving sound quality and directivity of a speaker through controlling the propagating direction and phase of the sound waves generated from a relatively small size noise source of office machines, and speakers, and so on.
(2) Description of the Prior Art
As the noise control device for reducing the noise, there have been conventionally known the lens- or prism-shaped noise control devices having numerous hollow conduit paths of different conduit path lengths, for instance, from Japanese Patent Publication No. 47,162/1980 and Japanese Utility Model Registration Publication No. 24,716/1983.
However, according to the structure of the noise control device in which differences in the conduit path length are provided by piling pipe members, parallel partition plates, or the like to form a hollow body with a number of hollow conduit paths and shaping the thus obtained hollow body into a lens or prism form as described in the above publications, unfavorably it is necessary to provide very long hollow conduit paths due to the relation to the wavelength in order to control even low frequency waves, thereby rendering the sound wave control device bulky.